List and dictionary instance applications (※)

One The sentence   It refers to a sequence of words connected by a single space , And there are no spaces at the beginning and end . Every word contains only lowercase or uppercase letters .

We can add... To a sentence from 1 Start word position index , And put all the words in the sentence   Out of order  .

For example , The sentence  "This is a sentence"  Can be scrambled to get  "sentence4 a3 is2 This1"  perhaps  "is2 sentence4 This1 a3" .
To give you one Out of order   Sentences  s , It contains no more than  9  individual , Please reconstruct and get the sentences in the original order .

example 1：

Input ：s = "is2 sentence4 This1 a3"
Output ："This is a sentence"
explain ： take s The words in are sorted according to their initial positions , obtain "This1 is2 a3 sentence4" , Then delete the number .

example 2：

Input ：s = "Myself2 Me1 I4 and3"
Output ："Me Myself and I"
explain ： take s The words in are sorted according to their initial positions , obtain "Me1 Myself2 and3 I4" , Then delete the number .

Code ：

public static string SortSentence(string s)
        {
            Dictionary<int, string> dic = new Dictionary<int, string>();
            List<string> ls = s.Split(' ').ToList();// String rotation list
            int ls_count = ls.Count;
            string res = "";
            for (int i = 0; i < ls_count; i++)
            {
                string[] vs = new string[2];
                vs[0] = ls[i].Substring(ls[i].Length - 1, 1);// Starting position , Number of interceptions 
                vs[1] = ls[i].Substring(0, ls[i].Length - 1);
                dic.Add(Convert.ToInt32(vs[0]), vs[1]);
            }
            int count = dic.Count + 1;
            for (int i = 1; i < count; i++)
            {
                res += " ";
                res += dic[i];// Dictionaries int,string adopt int Value string
            }
            return res.Trim();// Removes all leading and trailing white space characters from the current string .
        }